This circuit is for a siren that can be used with any of the above alarms and also other types. The circuit is from a Radio Electronics magazine from May 1975.
Analog Devives EVAL AD5941 Electrochemical Evaluation Board This board provided by Mouser...
Found in a Popular Electronics from the 90s, this Wien bridge oscillator uses a single-source...
Found in documentation from the 1980s, this circuit uses an operational amplifier from that time....